Internet service providers in the U.S. experienced a service slowdown Monday after fiber-optic cables near Cleveland were apparently sabotaged by gunfire. TeliaSonera AB, which lost the northern leg of its U.S. network to the cut, said that the outage began around 7 p.m. Pacific Time on Sunday night. The damage affected a large span of cable, more than two-thirds of a mile long, near Cleveland, TeliaSonera said. A source familiar with the situation said the lines are owned by Level 3 Communications Incorporated. Cogent Communications Incorporated warned that some customers may be experiencing disruptions because network lines had been cut somewhere between Montville, Ohio, and Cleveland. According to Keynote Systems Incorporated's Internet Pulse Report, Cogent was experiencing significant latency problems on Monday.